Hydraulic drive for a sliding combustion grate

ABSTRACT

The invention relates to a hydraulic drive for a water-cooled sliding combustion grate. Each displaceable grate stage ( 6 ) is connected to at least one connection rod ( 30 ) supported at the other end thereof on a crank ( 31 ), wherein the associated crankshaft ( 32 ) is supported in a bushing ( 33 ) penetrating the side wall ( 2 ) of the grate construction. A crank ( 34 ) connected to the piston ( 35 ) of a hydraulic cylinder-piston unit ( 36, 35 ) is seated on the other side of the crankshaft ( 32 ), outside of the actual grate construction of the associated grate run, where said hydraulic cylinder-piston unit is disposed. The hydraulic components are thereby spaced further away from grate plates, and not exposed to abrasion. Said components, being disposed remotely from the grate plates ( 6 ), can also be replaced during operation of the grate.

The invention pertains to a drive for water-cooled sliding combustion grate for refuse incineration plants which are especially suitable for burning of refuse and waste with high heating value. Such sliding combustion grates have fixed and movable grate stages made of grate plates or made of a row of grate bars in which the grate plates are laid out on top of each other in a stairway formation. These combustion feed grates can be installed in such a way that the combustion bed basically lies horizontally or else inclined, whereby slopes of 20 angular degrees or more are common. Grate plates are preferably made of steel sheets and they form board-shaped hollow bodies which extend over the complete width of the grate run. Water is channelled through these as a cooling medium. Every second grate plate is movable and can therefore execute a sliding or feeding stroke. When it concerns the feed grate, the movable grate plates can push the incinerator charge to the next underlying grate plate with their rear side. On the other hand, a reverse feed grate forms a virtually inverted, integrated, inclined staircase with overlapping steps. In the case of a reverse feed grate, the front sides of the movable grate plates carry the incinerator charge lying behind them back, after which this is again milled downwards in the direction of the slope of the grate. The movable grate plates, i.e. the respective grate plates located between two fixed grate plates, are moved to and from in the drop direction of their slope. This ensures that the refuse burning on the grate is constantly relocated with a high retention time of 45 to 120 minutes and is equally distributed on the grate.

European patent document, EP-0 621 449, discloses a water-cooled sliding combustion grate. This grate has grate plates which stretch over the complete width of the grate run and do not consist of multiple grate bars per grate stage. Like the stationary grate plates, the movable grate plates are fixed at the back to crossbars which collectively move forwards and backwards during operation and hence move the movable grate plates. European patent document, EP 0 874 195, shows a special construction of such a grate with individual drives for every single movable grate stage. Here the movable grate plates roll on the steel rolls and are also laterally guided on the horizontal rolls along the lateral end planks. The drive is implemented with every hydraulic piston-cylinder unit which impinges on the grate plates approximately at the centre and which is located directly under the grate plate.

The present drive construction is located under the grate, which means the associated hydraulic piston-cylinder units are also located underneath the grate. They are difficult to access there and are not accessible particularly during the operation of the grate due to the prevailing temperatures and due to possible slag falling through the grate.

The object of the present invention is therefore to create a hydraulic drive for a water-cooled sliding combustion grate which is particularly safe to operate, can be manufactured cost-effectively and can be easily mounted. Moreover, this drive should be easier to maintain, in that it is accessible during the combustion operation and the hydraulic piston-cylinder units of the individual drives of the grate plates can be replaced without the need for interrupting the operation of the grate.

The objective is achieved by a hydraulic drive for a water-cooled sliding combustion grate in which every movable grate stage of the grate construction is connected to at least one connection rod supported at the other end thereof on a crank, wherein the associated crankshaft is supported in a bushing penetrating the side wall of the grate construction and a crank connected to the piston of a hydraulic cylinder-piston unit is seated on the other side of the crankshaft.

First a sliding combustion grate with a conventional hydraulic drive is illustrated in the drawings and then this special hydraulic drive is presented here. The drive and its functions are further described below with the help of these drawings.

It shows:

FIG. 1: A sliding combustion grate in perspective view with partially removed grate plates;

FIG. 2 A longitudinal section through the grate run, with a view perpendicular to the grate run and the conventional hydraulic drive integrated under it;

FIG. 3: A cross-section through the framework of the grate and the substructure of the grate without the grate plates, i.e. the grate as shown in FIG. 1 seen from the front;

FIG. 4: The support members for integration between the two hollow profiles along the grate, seen from front;

FIG. 5: A movable grate plate seen from below;

FIG. 6: A perspective, schematic representation of the hydraulic drive for an individual, movable grate plate according to the invention, seen diagonally from above;

FIG. 7: A cross-section through a grate run with this hydraulic drive outside the side wall for the grate plates located to the left in the figure;

FIG. 8: A cross-section through two adjacent grate runs with the hydraulic drive covered by means of the sheet metal casing as a protective cover for the grate plates located on the left in the figure.

The basic construction of a sliding combustion grate with its important members, how it is presented during the construction, where the individual grate plates are still missing and the view of the substructure are evident from FIG. 1. Here it concerns a grate inclined downwards in the direction of flow. Two vertical, lateral steel walls 1,2, parallel to one another, are connected stably to one another with distancing bars 3,4. These distancing bars 3,4 run perpendicular to the grate and extend across the inside width between the two vertical steel walls 1,2 at two different levels. Both the steel walls 1,2 to the left and right of the grate can thereby consist of multiple steel sheets or parts which are screwed to one another in a suitable manner. Distancing bars 3,4, threaded at both ends, penetrate the two vertical steel walls 1, 2 and are screwed tightly to the vertical steel walls 1,2 by means of tapered ends and nuts. The top level of distancing bars or crossbars 3 also serve as supporting rods for the stationary grate plates 5 lying on top of them. The front edge of the bottom stationary grate plate 5 abuts against a discharge lip 7 welded in place between vertical steel walls 1,2, while its rear section is suspended over the first top distancing bar or crossbar 3. Next in line is a movable grate plate 6, the front bottom edge of which rests on the first stationary grate plate 5 below. The front bottom edge of the next highest stationary grate plate 5 rests in turn on movable grate plate 6 and so on. The sloped front side of the individual grate plates 5,6 is perforated by primary air slots 8, through which the primary air for the combustion is blown from below into the incinerator charge. Along the upper edge of steel walls 1,2 are two square tubes 9,10 disposed on top of each other in a slightly offset manner, the lower ends of which are sealed by welding, in that they are welded there. These square tubes 9,10 constitute the side panels of the grate run and restrict the sides of the incinerator charge bed when the grate is in operation. They are water-cooled and are forcibly flooded with water from bottom to top so that their insides are always completely filled with water. The individual grate plates 5,6 are made from sheet steel and are designed as hollow bodies that are forcibly flooded with water so that their insides are always completely filled with water and no air bubbles can be present inside. Alternatively, they consist of a support framework in which a free-flowing hollow body is inserted as a cooling body whereby this can then be covered by a wear plate which is interlocked with the support framework and the cooling body to ensure good heat transfer. All the sheet steel parts of the grate, whether square tubes 8,9 or grate plates 5,6, that come into contact with the incinerator charge are, therefore, continuously covered with water on the back side of the steel sheet or at least cooled by a water-cooled heat sink. Hence all the parts in contact with the fire are cooled continuously and kept at a stable temperature so that practically no dilatation occurs. This eliminates the need to provide compensating elements of any kind to the sides of the grate plates. The stability of the grate construction is essentially achieved by the distancing bars or crossbars 3,4, which strut and brace the two outer steel walls 1,2 on two parallel levels as already described. Between these two levels of crossbars 3,4, running along the grate on both sides of its centre are two other hollow profiles in the form of square tubes 11,12, which are connected at the bottom and at the top at some points to the crossbars 3,4, running perpendicular to them. One of the square tubes, namely square tube 11, feeds the cooling water from bottom to top for grate plates 5,6, while the other square tube 12 supplies flushing and cooling air for the hydraulic components of the drive of the movable grate plates 6. Support members 13 are installed for movable grate plates 6 between these two parallel-running square tubes 11,12. These support members 13 are fixed to the square tubes by two bolts that run through the two square tubes 11,12. For this purpose, the square tubes or hollow profiles 11,12 have welded-in crossbars with an inside diameter designed to accommodate the retaining bolts for the support members 13. The support members 13 themselves each have steel roll 16 disposed parallel to the corresponding grate plate plane, as well as a steel roll 17,18 to the left and right acting in the vertical plane. The movable grate plate 6 rolls off the last and the horizontal steel roll 16 serves as a lateral guide at the rear side of the grate plate 6. At the planks, i.e. at the square tubes 9,10, two horizontal steel rolls 19,20 are constructed for every movable grate plate 6 and these rolls are laterally guided into the plates from outside.

FIG. 2 shows an area of the grate with the conventional drive of the movable grate plate 6 as a longitudinal section seen from the side. The hydraulic cylinder 21, whose piston rods 22 reach the interior of the movable grate stage 6, can be recognised and the hydraulic cylinder 21 is hinged to a support member 13 with its rear side. At the rear, the grate plate 6 rolls off on the rolls 17 of the support member 13 which is fixed to the square tubes 11,12 by means of both bolts 14,15. Each of these support members 13 can be tilted backwards by removing the rear bolt 14 after which the pivot point of the hydraulic cylinder 21 is accessible and this can be readily dismantled. That can however take place only after decommissioning of the grate. The square tube 10 can be recognised behind the grate plates 5,6 which forms the lateral plank and below the side wall 2 with the crossbars 4.

In the case of constructions till now, the hydraulic drive is located directly under the grate plates as shown in FIG. 2 and that is now eliminated to eliminate any fire hazard under the grate. The hydraulic cylinder 21 with piston rod 22 is newly replaced by a mechanical connection rod which is hinged to a crank and the associated crankshaft is inserted externally through one of the side walls 1,2, so that the hydraulic components are completely obstructed outside the grate construction as illustrated subsequently.

FIG. 3 shows a cross-section through the grate framework and the grate substructure without grate plates as shown in FIG. 1, seen from the front. The side walls 1,2, the planks in the form of square tubes 9,10 as well as the crossbars 3,4 and the square tubes 11,12 in the middle extending along the grate can be recognised here. A single support member 13 as seen from the front is illustrated in FIG. 4 with the horizontal steel roll 16 for the horizontal guidance of the movable grate plate 6 as well as with the vertical steel rolls 17,18 for the carrying the movable grate plate 6.

FIG. 5 shows a single grate plate 6 or a support framework seen from below. The horizontal steel roll 16 lies in the recess 23 at the support member 13. The inside width of the recess 23 is chosen in such a way that it is slightly larger than the diameter of the horizontal steel roll 16 through which the grate plate is guided adequately in a transverse direction from the roll 16 to the grate run. The steel rolls 19,20 (FIG. 1) located at the planks 9,10 serve to guide the front side of the movable grate plate. The movable grate plate 6 has such recesses 24,25 at the bottom of its front side that it has a guiding area 26,27 on each of its sides, which runs parallel to the lateral surface of the grate plate 6, but it is repositioned against this surface. These steel rolls 19,20 roll off along this guiding area during inside and outside movement. Thereby every movable grate plate 6 effectively has a three-point bearing. At the centre back where the drive is located, the grate plate 6 is guided horizontally and vertically by the corresponding steel rolls 16,17,18 and at the front it is guided laterally to the left and right of the steel rolls 19,20 when the front bottom edge of the grate rests on the next stationary grate plate 5 that is lower and slides on it when moved back and forth.

The hydraulic cylinder 21 and its hydraulic lines are present directly underneath the grate according to the construction as per the FIGS. 1 and 2 as described previously and all parts are exposed to the downdraught which can have an abrasive effect over the years. The aim of the drive construction presented subsequently is to specify an alternative construction in which only heavy mechanical parts of the drive construction, which themselves do not have any other parts, are exposed to the abrasive effect of the downdraught and simultaneously locate drive parts that are sensitive to it outside the grate.

FIG. 6 shows this hydraulic drive for an individual movable grate plate 6 illustrated schematically as seen diagonally from above. The hydraulic cylinder under the grate plate is replaced by only a connection rod 30 which is hinged to a crank 31 which in turn sits on a crankshaft 32. The crank 31 has a slotted hole 38 in which the bolts 39 of the connection rod 30 are mounted because the connection rod 30 must move back and forth linearly in the direction of its course as shown with a double arrow when the crank 31 pivots back and forth angularly and consequently its end does not carry out a linear motion. The crankshaft 32 is supported in a bushing 33 which penetrates the side wall 2 of the grate construction and is stably welded or screwed to this. On the outside of the grate construction, the crankshaft 32 is equipped with another crank 34 which is hinged to the end of a piston rod 35 of a hydraulic cylinder 36. The cranks 31,34 can be simply plugged in at the crankshaft ends and can be secured with a lock nut. With its other end, the hydraulic cylinder 36 is hinged to a retaining bracket 37 which is fixed to the outside of the side wall 2 of the grate construction. The axle of the bushing 33 runs at a right angle to the direction of motion of the movable grate plate 6 and the crank 31 for the connection rod 30 at the crankshaft 32 can be mounted to the crank 34 at the other end of the crankshaft 32 by turning and swivelling by approx. 120° to 180°. When the crank 34 is actuated at this other end of the crankshaft 32 and the crankshaft 32 is turned correspondingly, the movable grate plate 6 is accordingly moved forward and backwards as with the forward and backward movements of the piston 35 by means of the hydraulic cylinder-piston unit 36. The crankshaft 32 can be turned by 0 to approx 60° by means of systematic controlling of the hydraulic piston-cylinder unit 35,36 so that the degree of thrust of the movable plate 6 can be continuously varied.

The hydraulic components are situated further away from the grate with this drive construction and are no more directly beneath the grate. Every single movable grate stage can be operated individually in this way via its own hydraulic cylinder-piston unit which is fixed to its side wall 2 on the outside of the grate construction.

A cross-section through the grate run with a view of the rear in the direction of motion of the movable grate plate 6 is shown in FIG. 7. A connection rod 30 is hinged to a recess at the bottom of the grate plate 6. The connection rod 30 is flexibly connected to the crank 31 which is at the bottom of the crankshaft 32 via the bolts 39. The crankshaft 32 is supported in the bushing 33 by means of the replaceable slide bearing 40. The bushing is stably connected to the side wall 1 of the grate construction 2 via the vane struts 41. These vane struts 41 are integrated with the corresponding recesses in the side wall 1 or 2 of the grate construction and are welded to them. The drive is present on the other side, of which the crank 34 and the piston rod 35 are illustrated in a section here.

FIG. 8 shows a solution for a drive when multiple grate runs 28,29 are located next to each other. The water supply lines for the grate plates 6 should therefore be indicated with 43 and the water discharge pipes of the grate plate marked on the right side should be indicated with 44. The hydraulic cylinder 36 of this drive described above is located completely outside the first grate run 28, but however lies under the grate plate 6 of the grate run 29 connected on this side of the grate. In this case it is however ensured that the hydraulic cylinder 36 is located further away from the grate plates 6 than the solution described previously and in the beginning. Moreover, the hydraulic cylinder 36 and its hydraulic feed and drainage pipes are surrounded by a steel casing 42 so that it is completely covered from above and only its piston rod protrudes at the side from a hole in the sheet-metal case 42. So it protrudes backwards from the sheet-metal case in FIG. 8 and consequently actuates the crank 34.

It is clear that such a drive, as shown for every single, movable grate plate 6, can be provided in duplicate execution and with a piston-cylinder unit at every side of the grate run. It is further possible to design all the grate plates of a grate as movable plates. The piston-cylinder units can also eventually be located in another mounting direction according to the space conditions. The individual hydraulic cylinders can also be arranged in a staircase manner over one another and mounted on the outside of the side wall. In the case of vertically arranged cylinders, the cranks at the crankshaft must be rotated by 90°. In the case of cylinders tilted at an angle of 45°, they should correspondingly be rotated by 45° opposite to the execution shown in the figures. To gain some space, multiple alignments can also be chosen interchangeably. 

1. A hydraulic drive for a water-cooled sliding combustion grate in which every movable grate stage (6) is connected to at least one connection rod (30) supported at the other end thereof on a crank (31), wherein the associated crankshaft (32) is supported in a bushing (33) penetrating the side wall (2) of the grate construction and a crank (34) connected to the piston (35) of a hydraulic cylinder-piston unit (36,35) located on the grate construction is seated on the other side of the crankshaft (32), outside of the actual grate construction of the associated grate run.
 2. Hydraulic drive for a water-cooled sliding combustion grate according to claim 1, characterised in that the axle of the bushing (33) runs at a right angle to the direction of motion of the movable grate plate (6) and the crank (31) for the connection rod (30) at the crankshaft (32) is mounted at the other end of the crankshaft (32) for the pistons (35) of the hydraulic cylinder-piston unit (35,36) by turning the crank (34) by 120° to 180°.
 3. Hydraulic drive for a water-cooled sliding combustion grate according to claim 1, characterised in that the bushing (33) contains the replaceable bearing (40) for the inserted crankshaft (32) and the cranks (31,34) can be plugged in at the crankshaft ends and can be secured with a lock nut.
 4. Hydraulic drive for a water-cooled sliding combustion grate according to claim 1, characterised in that the bushing (33) has at least two vane struts (41) radially distanced from it which are integrated in the corresponding recesses in the side wall (1,2) of the grate construction and are welded to it.
 5. Hydraulic drive for a water-cooled sliding combustion grate according to claim 1, characterised in that, for two grate runs (28,29) lying next to one another at which the hydraulic cylinder-piston unit (35,36) is located underneath a grate run (29), its own as well as its hydraulic lines on its upper side are surrounded by a sheet-metal case (42) so that only the piston rod (35) protrudes from the sheet-metal case (42).
 6. Hydraulic drive for a water-cooled sliding combustion grate according to claim 1, characterised in that two such drives are arranged for every movable grate plate (6).
 7. Hydraulic drive for a water-cooled sliding combustion grate according to claim 1, characterised in that the piston-cylinder units of the individual drives are continuously mounted in different directions. 